Sulfur transportation in pipelines

ABSTRACT

An improved method of transporting sulfur-liquid hydrocarbon slurries through pipelines without causing sulfur agglomeration, sticking, deposition or plugging of the pipelines. The invention relates to an improved and novel process of preventing sulfur agglomeration, sticking, deposition and plugging of pipelines transporting sulfur in the form of a sulfur-liquid hydrocarbon slurry.

C United States Patent [72] lnventor Ronald K. June 56] References Cited1 23 UNITED STATES PATENTS 121] P 2.798,772 7/1957 Redcay 302/14- [22]Filed Dec. 18,1968

3,368,876 2/1968 Bailey, Jr 302/14 [45] Patented M971 3 443 837 5/1969 M1 1 302 14 [73] Assign she Oil Company eyere a New York, N.Y. PrimaryExaminer-Andres H. Nielsen Attorneys-George G. Pritzker and J. H,McCarthy ABSTRACT: An improved method of transporting sulfurliquidhydrocarbon slurries through pipelines without causing [54] SUUTURTRANSPPRTATION [N PIPELINES sulfur agglomeration, sticking, depositionor plugging of the 5 Claims, No Drawings pipelines [52] U.S. Cl 302/66,The invention relates to an improved and novel process of 302/14preventing sulfur agglomeration, sticking, deposition and [51] Int. Cl865g 53/30 plugging of pipelines transporting sulfur in the form of asul- [50] Field oi Search 302/ 14, 16 fur-liquid hydrocarbon slurry.

SULFUR TRANSPORTATION IN PIPELINES BACKGROUND OF THE INVENTION Thetransportation of sulfur neat or as a water or oil slurry in pipelinesis well known in the art as noted by reference to U.S. Pats. Nos.2,798,772; 2,917,345 or 2,947,578 or as described in Pipeline Industry,June, 1967, pages 5860. In making the sulfur into a sulfur-hydrocarbonslurry, the sulfur is generally sprayed in molten form into either wateror a hydrocarbon to form a slurry suitable for transportation through apipeline. Formation of a stable slurry wherein the sulfur does notundergo any undesirable change or the slurry does not exhibit a tendencyto wide variation in viscosity is essential to the process in additionto other problems which may be encountered during and aftertransportation of the slurry through a pipeline. Thus, agglomeration andseparation of the sulfur from the carrier fluid, plating, depositing orcoating of the sulfur on pipeline walls causing plugging of thepipeline, corrosion, particle attrition and viscosity changes due topressure and temperature variations requiring greater pumping powerwhich increases operation costs, etc., are only a few of the problemsnormally encountered in transporting sulfurliquid hydrocarbon slurriesthrough pipelines.

Although the'above are serious problems for consideration intransporting sulfur through pipelines, nevertheless the transportationof sulfur in slurry form through pipelines can be made to be aneffective, attractive and economic means of sulfur transportation,particularly since sulfur is recovered or ob tained from isolated,remote and inaccessible areas, and must be transported to desiredaccessible areas. As noted above, a number of methods have been proposedfor pipeline transportation of sulfur slurries such as injecting moltensulfur into water or a liquid hydrocarbon thereby forming a sulfurslurry for pipeline transportation. These methods for making sulfurslurries suitable for transporting through pipelines generally do notovercome the agglomeration, attrition, deposition, sticking, coatingand/or plugging problems described above.

An object of the present invention is to transport sulfur as asulfur-liquid hydrocarbon slurry through pipelines which is stable andflowable.

Still another object of the present invention is to transport through apipeline sulfur-liquid hydrocarbon slurries without causing sulfuragglomeration, coating, deposition or plugging of the pipeline.

Still another object of this invention is to form a slurry of sulfur ina liquid hydrocarbon medium, which when formed is stable, does not tendto cause sticking, agglomeration or plugging of equipment during themaking of the slurry or on storage or pipeline plugging or cause anydifficulty in circulation of the slurry when said slurry is pumped andtransported through a pipeline and from which the sulfur can be readilyrecovered at the terrninal end of the pipeline as essentially puresulfur.

Another object is to transport sulfur as a liquid hydrocarbon slurry bypipeline over great distances under conditions of reduced pumping andhandling costs.

Other objects will be apparent from the following description.

SUMMARY OF THE INVENTION The present invention is directed to animproved, novel and new technique for making a sulfur-liquid petroleumslurry and transporting a slurry of a sulfur-liquid petroleum throughpipelines over great distances without causing sulfur agglomeration orsticking during the slurry preparation or on its subsequent storage, ifnecessary, or when pipeline transport ing the slurry so that sulfurdeposition on the walls of the pipelines due to the tendency of sulfurunder such conditions to adhere to the pipeline walls because oftemperature, pressure and other variable conditions so as to plug saidlines; by admixing or adding or injecting prior to or after injectioninto the pipeline ofa slurry of sulfur and a liquid petroleum, a smallamount of from 0.01 to percent, preferably between about 0.5 percent toabout 5 percent, of an asphaltenic material derived or obtained orpresent in crude oil and preferably an unrefined crude oil. Theasphaltenic material can be added to the slurry of sulfur and liquidpetroleum prior to or during the making of the slurry or the asphaltenicmaterial can be injected when necessary in various places along thepipeline where indications are that the slurry might cause sulfuragglomeration, deposition, sticking or plugging of the line. Anyplugging detection means known in the art can be used for this purpose.It has been noted that by adding or injecting into a slurry of thesulfur and liquid petroleum in which the sulfur content of the slurrycan vary from about 10 percent by weight to about 75 percent by weightor higher, preferably between 30 percent by weight and percent byweight, sulfur, e.g., kerosene or oil distillates or condensates orcrude oil during or after the slurry preparation from about 0.0l to 10percent of an asphaltenic material, that not only does its presenceprevent plugging of pipelines transporting said slurry but alsopreventing agglomeration, sticking and deposition of sulfur on the wallsof the pipelines and improves flow of the slurry and reduces pumpingcosts.

The sulfur-liquid petroleum slurry can by any suitable means such asdescribed in U.S. Pat. No. 2,798,772 or by the method described incopending U.S. Pat. application Ser. No. 663,755, filed Aug. 28, 1967which matured as U.S. Pat No. 3,443,837. It is preferred that in themaking the sulfur-liquid petroleum fraction slurry that the sulfur isproduced in spherical form since sulfur in this form in the slurry ismore stable and is resistant to agglomeration, separation, attrition andfriction.

The phase transfer method for making the sulfur slurry as described inthe above-mentioned copending application comprises first forming asulfur-aqueous liquid (water) slurry and thereafter phase transferringthe sulfur particles from the aqueous liquid into a liquid hydrocarbon.Thereafter, the crude oil can be added as desired.

The liquid petroleum carrier for the sulfur can be one ranging inviscosity from a light petroleum fraction such as liquefied petroleumgas (LPG), gasoline, kerosene, fuel oil, lube oil, petroleumdistillates, condensates, crude oil and mixtures thereof. Preferred areliquid petroleum containing at least 10 percent or higher of aromatics,preferably about 15- 30 percent aromatic enriched kerosene or oilcondensate fractions or crude oil containing 15-80 percent aromaticswhich include monoand polyaromatic hydrocarbons.

The asphaltenic additive can be obtained from unrefined or refined crudeoil and fractions thereof. By unrefined crude oil is meant any crude oilwhich has not been processed in a refinery. Thus, a crude oil may beused as it is removed from the ground, or it may be first processed infield units such as oil-water separators, degasers, etc. Although justhow the asphaltenes function in the slurry mixture is not understood, ithas been found that the asphaltenes prevent sulfur agglomeration,sticking and aid in the formation of spherical sulfur particles havingdimensions of from 1 to 800 microns and preferably between 20 and 400microns.

The asphaltenes can be recovered from petroleum stocks by any suitablemeans such as described in the Journal of the Institute of Petroleum,Feb. 1968, pages S053 and Apr. 1968, pages 107-1 14 or as described inU.S. Pats. No. 3,206,388; 3,228,870; 3,153,623; 2,729,589; 3,368,876;3,364,138; 3,206,388 and 3,275,076. The latter two patents basematerials can be used per se as the asphaltene additive and carrier forthe slurry. In other words high asphaltenic crudes or fractions thereofcontaining at least 1 percent asphaltenes can be used both as thecarrier and additive for the sulfur slurry. The asphaltenes,asphaltogenic acids and carboids and their method of recovery andseparation from crudes and fractions thereof is also fully described inchapter 9 of the Sachanens book on The Chemical Constituents ofPetroleum" and includes petroleum resins, asphaltenes, asphaltogenicacids and their derivatives. Also, the asphaltenic materials describedin U.S. Pat. No. 3,275,076; 3,284,340 or 3,336,146 can be used and theycan be separated from petroleum by methods described in U.S. Pats. No.3,364,138 and 3,368,876.

During the preparation of the slurry as the molten sulfur is dispersedinto liquid petroleum containing active asphaltenic components to aid inthe making of spherical sulfur particles as well as preventagglomeration, sticking and the like, the slurry can be cooledeffectively by vapor cooling such as described in U.S. Pat. No.2,632,691 or by use of volatile organic materials such as low molecularweight hydrocarbons or chlorinated hydrocarbons in which case theprocess should be carried out under pressures as described in U.S. Pat.No. 2,316,673.

At the terminal end of the line the sulfur can be readily separated fromthe slurry by any suitable means.

desirable since spherical sulfur particles in slurries as definedprovide optimum pipeline performance such as low pressure drops duringits transportation and ease of recovery and pu rification at theterminal end of the pipeline.

The following examples illustrate the essence of the present invention.

A. Molten sulfur at 120- 180 C. was sprayed into aromatic (17 percent)enriched kerosene through a spray nozzle at about 200 psi. pressure dropto give a homogeneous slurry with sulfur solids content of about 16percent volume in which the sulfur particles were essentially largeangular-crystalline particles which began to stick together andagglomerate into a sticky mass within about lOl5 minutes.

TABLE 1B.--EFFECT OF ADDITIVES ON SULFUR DISPERSION INTO PETROLEUMFRACTIONS [Conditions: 500 ml. carrier in 1-liter Morton flask. 90 ml.sulfur at approximately 140 C. added in 0.5-minute. 1,200 r.p.m. withcrescent blade stirrer, except as noted] Coagulum (+12 Wt., mesh),median Particle Initial Level, percent particle sphericity temp percentwt. basis size, percent, Carrier wt Type S is (1 1.1. wt.

Experiment:

1 Petroleum traction (Waterton condensate) 22 None 19.1 680 4 2 .110 b L1 Bry on 430( alkylarylsulfonate). 20. 4 710 5 24 1 Oleic acid-. 30 7701 21 1 50% dodecyltrimethyl ammonium 13.8 700 15 chloride. '22 1Dodecylamine 8. 630 21 22 1 Asphaltenes N11 600 57 23 0.1 ..do 4.9 70054 23 0. 1 6 API crude percent wt. 7. 0 690 39 asphaltenes). 24 1 Crudeoil deasphalted residue resins. 6. 3 680 55 25 1 Crude oil deasphaltedresidue 20. 3 680 0 aromatics. 11......... Hexane 22 0.1 Asphaltenes 8.0730 43 12 Fresh Medicine River crude oil d 60 None 1.4 315 91 13Deasphalted Medicine River crud 60 None (3.9% asphaltenes removed) 5. 7400 12 14 White oil (Viscosity 25 C., 172 cs.) 60 5 2.9 API crude oil(17 percent wt. Nil 135 B5 asphaltenes) n Portion of 30, +50 mesh sulfurparticle fraction which rolls down an inclined phase (s1ope=1 in 12).

b Derived from Canadian oil field. AP1gravity=54.9; viscosity, cs. 59 F.=0.95 and 77 77 F.=6.9; B.S. and W. percent vo1.=0.6; flash point, tagopen cup, F.=32; pour point, F.=70.

FIA, percent vol. saturates=82 and aromatics=18.

6 API gravity=35.6; viscosity, cs. 59 F.=9.1 and d 600 r.p.m. agitatorspeed used in all 60 C. runs.

' PREFERRED EMBODIMENT OF THE INVENTION (l) A 40-60 percentsulfur-aromatic 17 percent) enriched kerosene slurry was prepared byphase transfer by first injecting molten sulfur into an aqueous liquidsuch as water and thereafter contacting the slurry thus formed with thearomatic enriched kerosene to effect phase transfer of the sulfur particles into the aromatic enriched kerosene. To the sulfurkerosene slurrywas added from about 1 percent to about 2 percent of asphaltenes andthereafter this slurry was injected into a pipeline for transportationto a terminal station. Sulfurkerosene slurries containing a small amountof crude oil thus formed do not fonn agglomerates or did they plug thepipeline. lnstead of using the phase transfer technique for making theslurry, molten sulfur can be injected into the kerosene directly andthereafter admixed with a small amount (l2 percent) asphaltenes.

(II) An advantage of the present process for transporting throughpipelines sulfur-liquid petroleum slurries as defined is that the slurrycan be also prepared by direction injection of molten sulfur into asuitable petroleum fraction such as kerosene, fuel oil, oil condensateor distillate crude oil and mixtures thereof to which has been added asmall amount of asphaltenes so as to aid in making spherical sulfurparticles and prevent sulfur agglomeration, deposition and plugging ofpipelines. Either process as well as other processes can be used to makethe sulfur-liquid petroleum fraction slurry depending on theavailability of the carrier. Thus, where water is available the firstprocess can be used and if not the second one can be used.

The presence of a small amount of an asphaltenic material during thepreparation of the slurry by method (1) or (ll) has an additionaladvantage in that an asphaltenic material aids in the formation ofspherical sulfur particles which are most F.=0.87; flash point, tag opencup F.=7; pour point F. e

B. The method of (A) was repeated except that 1 percent of asphalteneswas added to the kerosene carrier. The particles formed weremicrospherical (l0450 microns) in shape and no tendency of the particlesto stick or agglomerate were observed for over 24 hours.

In another test different petroleum fractions were used to form sulfurslurries wherein a -ml. portion of molten sulfur at C. was injected as acontinuous stream for 0.5 minute into a well-stirred 500 ml. charge of apetroleum carrier. As shown in Table 1 some of the carriers were usedneat and to some were added crude oils or crude oil residue products.For comparison various surfactants were also tested as additives to thecarriers as shown in Table 1.

From Table 1 it can be seen that only the carriers containing theasphaltenes added as such, or that are indigenous to heavy crude oils,perfonned satisfactorily. That is, with asphaltenes predispersed in thecarriers, high degrees of sulfur particle sphericity were attained andat the same time agglomeration losses of sulfur particles to coagulumwere suppressed.

Sulfur slurries of the present invention containing small amounts ofasphaltenic additives can be transported through pipelines over greatdistances without the danger of sulfur deposition, agglomeration,sticking or plugging of the pipelines.

At the terminal end of the line the sulfur can be removed from theliquid hydrocarbon by suitable means such as described in U.S. Pat. No.2,798,772 and the sulfur purified by methods as described in U.S. Pat.No. 2,809,885 or as described in the copending U.S. Pat. applicationSer. No. 684,507, filed Nov. 20, 1967 which matured as U.S. Pat. No.3,489,677 which comprises treating oil contaminated sulfur with anaqueous solution containing a mixture of alkali hydrosulfide andcorresponding hydroxide, e.g., ammonium hydrosulfide and ammoniumhydroxide or by other suitable means such as sulfur can be recoveredfrom the oil slurry by centrifugation or filtration of particulatesulfur, melting the particles and liquid-liquid extraction with ahydrocarbon solvent containing l0-50 percent aromatics. Thus. at thereceiving terminal the sulfur slurry be filtered and washed. Therecovered sulfur is then melted and purified by liquidliquid extractionwith an aromatic hydrocarbon such as cumene. Also, if desired, thesulfur can be steam stripped to remove any dissolved solvent and thenfiltered to recover bright yellow sulfur.

The foregoing description of the invention is merely intended to beexplanatory thereof. Various changes in the details of the describedmethod may be made within the scope of the appended claims withoutdeparting from the spirit of the invention.

lclaim:

l. A method of transporting sulfur through a pipeline to a terminalwithout causing sulfur sticking, agglomeration and plugging of the linecomprising:

a. mixing with a liquid petroleum fraction selected from the groupconsisting of petroleum distillate and petroleum condensate fractions, asmall amount of from about 0.1

percent to about 10 percent of an asphaltenic material to form a liquidpetroleum mixture;

b. injecting l075 percent molten sulfur into liquid petroleum mixture(a) to form a sulfur-liquid petroleum mixture slurry;

c. injecting the slurry (b) into a pipeline; and

d. transporting via said pipeline slurry (c) to a terminal station.

2. The method of claim 1 wherein the liquid petroleum fraction of (a) isa petroleum condensate containing from l0 percent to 30 percent aromaticcomponents.

3. The method of claim 1 wherein the slurry contains 30- 70 percent byweight sulfur and the balance being a liquid petroleum condensate andthe asphaltenic material is asphaltene present in an amount of fromabout 0.5 percent to about 5 percent.

4. The method of claim 1 wherein the slurry is separated into itscomponent parts at the terminal end of the pipeline.

5. The method of claim 4 wherein the separated components of sulfur andpetroleum fractions are each purified by removal of contaminantstherefrom.

2. The method of claim 1 wherein the liquid petroleum fraction of (a) isa petroleum condensate containing from 10 percent to 30 percent aromaticcomponents.
 3. The method of claim 1 wherein the slurry contains 30-70percent by weight sulfur and the balance being a liquid petroleumcondensate and the asphaltenic material is asphaltene present in anamount of from about 0.5 percent to about 5 percent.
 4. The method ofclaim 1 wherein the slurry is separated into its component parts at theterminal end of the pipeline.
 5. The method of claim 4 wherein theseparated components of sulfur and petroleum fractions are each purifiedby removal of contaminants therefrom.